JP2002531001A - Logical node identification in information transmission networks - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a more efficient automatic method of reallocating a channel for use of a node in an information transmission network. A system for generating and transmitting a logical node identification signal as part of a data stream is disclosed. The system also includes a subscriber station capable of receiving and extracting logical node identification information from the data stream. The subscriber station creates a new message containing the logical type node identification signal and sends the message to the transmitting network system control, so that the switching of the data stream to the corresponding channel on the information transmitting network depends on the network topology. Made in connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates generally to the field of information transmission networks, and more particularly, to logical node identification of such networks. More particularly, the present invention relates to logical node identification of such networks that support session-based routing / switching of information flows in heterogeneous networks. 2. 2. Description of the Background Art In the field of information transmission, routing and switching of information to a destination node is most commonly accomplished in one of two ways. Either (1) a symmetrically switched virtual path / circuit (ie, ATM), or (2) a packet-based routing network (ie, the Internet). The third type of network for routing / switching information comes in many forms and is well supported by asymmetrically switched virtual paths / circuits or variants of two methods with asymmetric packet routing.

[0002] This third area can be classified into two categories. That is, first, a set of information transmitting networks (ie, streaming network flows for video and audio, and usually outgoing networks) that require a combination of tightly connected packet routing networks with asymmetrically switched networks. Bi-directional multimedia content delivery such as video-on-demand, which requires an out-of-band IP network to handle the source and destination in both directions. The second is the knowledge of access points in packet-based networks. A set of information transmission networks that can be used to improve network latency (ie, dynamic routing changes that need to support a particular roaming laptop computer). The present application addresses this first case.

[0003] The former category of information transmission networks is one to which the present invention addresses in detail. In particular, video-on-demand interactive multimedia services over fiber optic and coaxial hybrid (HFC) networks have recently existed for cable services. In this case, one-way content streaming (video and audio streaming to a home digital set-top box whose content is QAM-modulated) and IP bidirectionality (downstream to home via out-of-band, and subscriber There are various return path packet forwarding connections from the set-top box to the cable headend device. This same solution is for broadcasts on satellites (content delivery) that use radio (cell phones) or telephone modems to be bidirectional, as well as for terrestrial broadcasts (eg, MMDS, LMDS). Can be used. It is noted that control sessions via out-of-band can also be multiplexed to in-band streaming links.

A technique for increasing the number of simultaneously transmitted video-on-demand programs is through channel reuse. In that case, programs are assigned to channels at intermediate nodes (commonly referred to as "remote headends" or "hubs"), where the lines from individual subscriber stations are connected to the main CATV network. For the purposes of the present invention, the term "headend" is defined as a physical site, on which devices for modulation, demodulation and processing (such as control, monitoring, etc.) are mounted, with or without an operator Alternatively, it is operating at an operator-less site that is remotely monitored to determine if it is operating as specified for other transmission means, such as cables or MMDS. This technique allows the same channel to be assigned to another program at another node (known as spectrum reuse by physical media partitions). Thus, a dedicated video-on-demand channel can transmit programs to one set of subscriber stations connected to a first hub, while another set of subscriber stations connected to a second hub using the same channel. Can send different sets of programs to

[0005] Usually, the provision of a video-on-demand service is performed by a session control manager (
SCM) by assigning it to one or more hubs. The SCM is responsible for receiving requests from set-top boxes at the responsible hub and providing requested services. Therefore, each SCM must be informed of the subscriber station corresponding to the assigned hub. Based on this topology information, the SCM provides information for creating virtual circuits from the video server to the QAM modulator, and thus provides an access mechanism to video and audio streams from the set-top box. The SCM also tells the set-top box what frequency the demodulator should tune to and what packet identification number (PID)
) Tells you whether to filter video and audio streams.

When subscriber stations are added or deleted, the mapping between the SCM, hub, and set-top box must be changed, as well as new subscriptions or subscription cancellations. For example, a set of QAM channels can only accept a particular number of subscriber stations. If the number of subscriber stations on the hub exceeds the capacity of the allocated stream, further logical node partitioning will occur on the hub. Although such changes can be made manually to the mapping information in the headend, a more efficient automatic method of reassigning channels for node use is desired. SUMMARY OF THE INVENTION In a principal aspect, the present invention provides for automatically transmitting information about a corresponding session control manager to a subscriber station and for connecting a channel group defined as a node.

In accordance with the principles of the present invention, a video-on-demand (VOD) system includes a plurality of session control managers to send a requested program to a subscriber station. A video-on-demand system is a spectrum reusable network between a subscriber station and one of a corresponding plurality of nodes, connected to a plurality of subscriber stations, where the nodes are connected to the video-on-demand system and the subscriber station. It is located between them. The video-on-demand system includes a logical node assigner that assigns a logical type identification to each node and identifies a correspondence between each node and one of the corresponding session control managers. For example, HFC
Logic type nodes are defined as a group of fiber nodes sharing the same QAM modulation spectrum (ie, the same stream in the VOD channel).

According to a further aspect of the present invention, a logical node assigner periodically transmits node assignment information to each node on the network to uniquely identify a logical node, and also for each node. Identify the corresponding session control manager. This allows the subscriber station to tune to this digital channel at any time and get this information when needed. Such techniques include the session control manager,
It is advantageous in that it allows automatic distribution of information about the logical nodes and the mapping between the subscriber stations. The result is a reduction in the complexity and overhead of managing a video-on-demand system, thereby reducing the overall cost.

The principles of the present invention are particularly advantageous in optical fiber coaxial hybrid (HFC) systems used for video program transmission. However, the principles described here are based on direct broadcast satellite (DBS) systems, local multipoint distribution services (LMDS), and multi-channel multi-unit distribution systems (MMDS).
) Can also be used.

One particular advantage of the present invention is that due to the automatic identification of the logical node with which each subscriber station is associated, the present invention allows the unidirectional node to receive information from the subscriber station for reception by the subscriber station. It allows the VOD stream of the cast to be switched to the appropriate QAM modulator to perform the modulation. This is a particular advantage, as new logical nodes are created, or the current node is split as the demand for subscription and service increases.

[0011] These and other features and advantages of the present invention will be further understood by considering the following detailed description of the preferred implementations of the invention. In this description, reference is often made to the accompanying drawings. With reference to the detailed illustration of the preferred embodiment, it illustrates a preferred embodiment of the system 100a constructed in accordance with the present invention. The system 100a includes a logical node identification (ID) generator 102,
Preferably, it comprises a signal source 104, a combiner 106, an information transmission network 108, and an information distributor 110. The invention has a particularly great advantage as it inserts a logical node identification signal into the data stream. The logical node identification signal is transmitted over network 108 and then sent back to SCM 224 (see FIG. 2B) to determine the exact configuration of system 100a.

This first embodiment shows the most general implementation of the invention, and therefore only the general terms will be described here. 2A and 2B show a more specific embodiment of the invention for a particular transmission network and will be described in more detail.

The logical node ID generator 102 generates at least one unique logical node ID number, and transmits this unique identification number as a signal to the output of the logical node ID generator 102. Logic node ID generator 102 preferably generates a plurality of unique identification numbers, which are sent to combiner 106 and combined with other information according to the node or location at which the information is being transmitted. . An output of the logical node ID generator 102 is connected to an input of the combiner 106. Video, sound, or
A signal source 104 that provides a data signal, such as in a digital video signal, is provided at the output of signal source 104 and is also provided to combiner 106. The output of signal source 104 is connected to a second input of combiner 106.

The combiner 106 has one or more outputs connected to an information transmission network 108 for transmitting a combined signal, the combined signal comprising an address for information, a signal source 1
04, and a logical node ID signal, which is sent from the logical node ID generator 102 to the information distributor 110 connected to the remote end of the transmission network 108. In a preferred embodiment, transmission network 108 includes one or more stream channels 202 for transmitting information from combiner 106 to downstream devices on a remote end of information transmission network 108. The information transmission network 108 also includes a configuration and control channel 204 for sending signals along a reverse path between the information distributor 110 and the combiner 106.

An information distributor 110 is connected and transmits and receives signals on the information transmission network 108. The information distributor 110 is also connected to a plurality of devices (not shown) such as a set-top box by a plurality of signal lines 120 to 132. The information distributor 110
The stream channel is received, and the source signal and the logical type node ID are transmitted according to the node ID number via the corresponding one or more signal lines 120 to 132. For example, a group of signals having video content and a logical node ID number 1 that is sent over the information transmission network 108 and received by the information distributor 110 will be transmitted only over the signal line 120. The video content and the logical node ID are not transmitted via the signal lines 122 to 132 of the other nodes 2 to n. Other combined signals will be transmitted in the same manner via respective signal lines 122-132 corresponding to their logical node ID identification numbers. As shown in the figure, each logical node identification number such as the logical node 4 is assigned to the signal line 1.
It may correspond to a plurality of signal lines such as 26, 128, and 130. In one embodiment, the signal lines 122-132 may form a hybrid coaxial with the optical fiber. Thus, the information distributor 110 effectively separates the data flowing on the stream channels 202 for distribution over individual signal lines or over groups of signal lines that correspond to channel reuse.

The information distributor 110 also receives a plurality of signals sent by the device (not shown) to the information distributor 110 in the upstream direction. The information distributor 110 then sends this signal to the combiner 106 via the configuration and control channel 204. In this way, a particular set-top box (see STB 220 in FIG. 2B) or subscriber station
A signal including the logical node ID can be received, the logical node ID can be incorporated in addition to the number identifying the subscriber station, and the information distributor 110 and the combiner 106 via the configuration and control channel 204. And the built-in signal can be sent in the upward direction. Using this information, the SCM 224 can determine the correct configuration of the network and nodes and make any necessary changes (eg, create new nodes, remove nodes, or remove nodes) to maximize network bandwidth usage. Do).

Referring now to FIG. 2A, a second embodiment 100b of a system configured in accordance with the present invention is shown. In the second embodiment 100b, similar components having the same function are denoted by similar reference numerals for easy understanding and convenience. Second
Embodiment 100b includes a logical node identification (ID) generator 102, a signal source 10
4, combiner 106, and stream channel 202a and return channel 204a
Including transmission networks of the form The information distributor includes a receiver and a descrambler 210.
a and telephone 214a.

The logical node identification (ID) generator 102, signal source 104, and combiner 106 are the same as described above with reference to FIG. However, in this embodiment, combiner 106 transmits the combined signal to a satellite station having one or more bases for uploading to the satellite. The satellite then receives the combined signal including the logical node ID and sends it to the receiver and descrambler 210a. Although only one receiver and descrambler 210a is shown for one satellite, those skilled in the art will appreciate that many receivers and descramblers 210a for each satellite.
It will be appreciated that there is a preference.

The receiver and descrambler 210a receives the combined signal from the satellite, descrambles the signal, and sends the combined signal to one or more devices 212a connected to the receiver and descrambler 210a. Telephones 214a to 214n are also connected to the receiver and descrambler 210a, and telephone lines 204a to 204n are connected to the coupler 106. A telephone path and a public switched network provide a return path. These, as is well known in the art, will recognize that telephones 214a-214n and telephone lines 204a-204n may be cellular or wireless telephones. Thus, the receiver and descrambler 210a communicate with the device 212a to determine channel selection and node ID, and
The information can be sent back to the combiner 106 via 204n. In this manner, system 100b is inserted by coupler 106 and devices 212a-2
Through the use of 12n and receivers and the logic node ID signals returned by the descramblers 210a-210n, it is possible to define multiple logic nodes, change or modify the nodes as desired, and verify the network configuration. it can.

Referring now to FIG. 2B, a third and preferred system embodiment 100c configured in accordance with the present invention is shown. The third embodiment 100c utilizes the capabilities of a conventional cable system to provide the stream channel 202b, and utilizes the return channel provided by the video-on-demand system as a return path. The third embodiment 100c has a logical node identification (ID) generator 102b.
, A video server 104b as a signal source, a digital video modulator (DVM) module 106b, an optical fiber 202b as a transmission network, a control channel modem (CCM) 222 and a session control manager (SCM) 224 providing a return path 204b, and information. It is preferable to include a distributor 110b. The system 100c has the advantage of using multiple DVMs 106b, each of which has multiple channels. Each DVM 106b preferably provides a video stream to various logic nodes. Thus, the automatic identification of the boolean nodes in the return channel allows the SCM to determine which DVM corresponds to a particular set-top box 220 and which video streams and channels are provided by it.
224 is determined. This is a particular advantage. This is because it is usually necessary to arrange the set-top box 220 between the logical node and the DVM channel.

The DVM module 106b receives a video signal from the video server 104b and a node ID signal from the logical node identification (ID) generator 102b. DVM
Module 106b combines these signals and sends them to information distributor 110b via transmission channel 202b. The SCM 224 controls the mixing of the content provided by the video server 104b and receives communications on the reverse or return path 204b via the CCM 222. For example, some of these components can be found at the headend in common on-demand cable systems. The information distributor 110b divides the signal received from the DVM module 106b, and separates each signal line 12 according to the logical type node ID assigned to each signal.
It is output on 0-132. For example, a plurality of set-top boxes 220a-
220n is connected to the line 120 to form the logic type node 1. Other signal line 1
Each of 22-132, or a group of signal lines, is similarly connected to form a logical node of the network. All of these exemplary systems are described in
No. 08 / 984,710, filed on Sep. 4, 2016, entitled "System for Two-way Distributed Information Services" and is incorporated herein by reference.

In the third embodiment 100c, the logical node generator is preferably a part of the transport processing module 102b. Transport processing module (TPM) 102b adds control signals and data to the stream generated by DVM 106b. TPM 102b is preferably connected to session control manager 224 and CCM 222 through a VMEbus architecture. More specifically, the TPM 102b also stores the program-specific information (P
Identification information such as SI) and packet identification information is added to the video and audio contents provided by the server 104b.

In FIG. 3, a plurality of subscriber stations 305-308 are connected by an information transmission network 302 to a cable head end 304 to receive video program services. The subscriber stations 305-308 preferably take the form of digital set-top boxes capable of requesting video programs from the headend 304. However, the subscriber station 305
308 provide information from the network 302 in other forms, for example, to another type of output device, such as a cable modem with a personal computer or an ADSL modem with a set-top box. Is also good. Subscriber station 3
05-308 are shown schematically, each showing subscriber stations 305-308 representing a plurality of subscriber stations.

Although only shown very schematically, headend 304 includes the necessary equipment and the ability to provide subscriber stations 305-308 with on-demand services such as, for example, video-on-demand services. In the video-on-demand service, a user requests a particular movie via a subscriber station, and headend 304 responds by sending data representing the movie to the requesting subscriber station for the user to watch. Multiple Session Control Managers (SCMs) 314, 315, 316 and 317
04. The SCM communicates the requested program in the form of a data stream to the transmission network 302 while executing various system commands and controlling functions. The SCMs 314, 315, 316 and 317 have the ability to originate streams to be propagated to subscribers in broadcast, multicast or unicast mode. As used herein, the term "broadcast" refers to the transmission of data for reception by all subscriber stations on a network. "Unicast" means the transmission of data for reception by only a single subscriber station on the network,
"Multicast" means the transmission of information for reception by more than one and less than all subscriber stations on a network.

In particular, each SCM 314-317 transmits to a subscriber station via an information channel of the network 302, modulates the baseband data stream on a carrier signal and adapts the signal to a conventional CATV frequency spectrum. And transmits the up-converted video signal. As an example, the data modulation of the downstream stream performed by the SCM is 64-ary quadrature amplitude modulation (QAM), and the transmission frequency is in the range of 54 to 860 MHz. These techniques are merely exemplary of representative transmission mechanisms, and other modulation schemes and frequency bands may be used.

The SCMs 314 to 317 transmit control information to the subscriber stations 305 to 308 via the downstream stream command channel of the transmission network 302. As an example, such control information may be 54 to 860 MHz using a bandwidth of 1 MHz.
Frequency multiplexed with the information channel to achieve transmission on carriers in the z range. Subscriber stations 305-308 communicate with corresponding SCMs 314-317 via reverse (backward or upstream stream) channels. In an embodiment, each SCM 314-317 supports 16 such reverse channels. Each reverse channel carries, for example, a BPSK modulated signal on a carrier in the range of 5 to 42 MHz. In this case, the channel capacity is approximately 64 Kbp
s. The exact frequency, modulation type, or channel capacity is not critical and may change. Further details on the operation of the SCMs 314-317 and other components of the headend 304 that provide VOD services can be found in US patent application Ser. No. 08 / 08,464, filed Dec. 4, 1997, assigned to the assignee of the present application. No. 984,710, entitled "System for Information Services Distributed Two-Way". This disclosure is incorporated herein by reference in its entirety.

The transmission network 302 preferably takes the form of an optical fiber coaxial hybrid (HFC), in which case the headend 304 is connected to the hubs 309-312 by optical fiber cables. Hubs 309-312 are connected by coaxial cables to the corresponding subscriber stations. Each hub 309-31
2 typically has the capacity to support hundreds to thousands of subscriber stations. Hubs 309-312 are preferably of conventional type.

The VOD service sends the requested video program using a number of predefined channels for the information channel. As an example, the number of available channels used by the VOD service is 2, 4 or 8 analog channels. Network 302 and headend 304 perform spectrum reuse at hubs 309-312 to increase the number of available channels for VOD services.

Each logical node (VOD channel per hub 309-312) has the ability to service a limited number of subscriber stations. Thus, the number of logical nodes required is approximately proportional to the number of subscribers served by system 100c. By way of example, each 64QAM channel can typically serve up to 80 subscribers. Depending on the number of subscriber stations connected to a particular hub 309-312, a particular logical type node may serve only a portion of the subscriber stations on one hub or only one hub. Either all of the above subscriber stations can be served, or subscriber stations on more than one hub can be served. Each of these scenarios is shown in FIG. For example, the SCM 314
Serving subscriber stations 9 and 310. This usually occurs in situations where hubs 309 and 310 are not completely populated by subscriber stations 305, 306, or where initial service is less pervasive. SCM31
5 serves only the subscriber station 308 on the hub 312. Hub 311
Is associated with SCMs 316 and 317 to service subscriber station 307. This situation occurs when the hub is connected to more subscriber stations than the capacity of a particular SCM, and requires many logical nodes. As the number of subscriber stations increases or decreases for a particular hub, the mapping between SCM logic nodes and subscriber stations needs to be changed. This may occur, for example, when a new home is built, when a current subscriber cancels a subscription to the services provided by headend 304, or when a new subscriber is added.

In accordance with the principles of the present invention, SCMs 314-317 can be automatically deployed to subscriber stations 305-308 based on network 302 topology changes. This is advantageous in that it is performed by determining the number of subscriber stations connected to each hub and by sending a logical node identifier (ID) to each subscriber station. The logical node ID provides the correspondence between the SCM and the corresponding subscriber station. For example, in FIG.
5 and 306 correspond to the first logical type nodes from nodes 1-4, and subscriber station 307 has at least two nodes from nodes 11-20 and other nodes 21-n.
Corresponding to the three (third and fourth) logical type nodes and the subscriber station 312
Corresponds to the second logical type node from nodes 5-10.

The logical node ID for a subscriber station on the network 302 is preferably determined periodically and transmitted to the subscriber station periodically. The logical node ID is an MPEG-ID containing appropriate header information having the logical node ID.
It is preferably transmitted as an II (Motion Picture Expert Group, Type II) packet. MPEG type encoding is a common protocol for encoded video data, and is therefore a convenient protocol for encoding logical node IDs. However, the exact manner in which the logical node ID is encoded for transmission is not critical, and other encoding techniques may be used within the principles of the present invention.

FIG. 4 of the drawings shows, as an example shown in FIG. 3, a method of transmitting a logical node ID. In FIG. 4, subscriber stations 305 and 306 are part of a first logical type node. This information is sent from the headend 304 to the subscriber station 305
306 by sending the logical node ID1 to the subscriber station 30.
5-306. Subscriber station 308 is part of the second logical type node. This information is provided to the subscriber station 308 by transmitting a logical node ID for the second logical node from the headend 304 to the subscriber station 308. The subscriber station 307 is part of either the third logical type node or the fourth logical type node. Corresponding node information (third
The logical node ID or the fourth logical node ID is transmitted to the corresponding subscriber station 307.

The introduction of a logical node ID into the video stream and its use to identify the channel serving a particular subscriber station is a particular advantage. Provision of a logical node ID signal in the video stream allows the subscriber station to move anywhere in the network to obtain a switched video stream to the subscriber station based on the new logical node ID. Become. For example, a particular subscriber station may be initially connected to the network and assigned a logical node ID1. All information for the subscriber is provided, including subscriber station specific information. However, when users move geographically,
A subscriber station may be picked up and accessed from a new location served by another logical node. Since the IDs of the different logic type nodes are part of the stream, once it is provided to the relocated subscriber station, headend 304 provides the signal which channel is intended for the user. Recognize. This eliminates the need for manual network recognition that was required in the prior art. Rather, according to the present invention, it can be said that the service can be updated with the channel and DVM information that is easily updated in the SCM. Another example where the provision of a logical node ID has particular advantages is when a new node is created or deleted due to a change in the number of subscribers on a particular channel. The use of logical node IDs eliminates the need for manual configuration changes.

The method of the present invention for transmitting and using a logical node ID signal as part of stream data will now be described in more detail with reference to FIGS. 5 to 7. First, a general method will be described with reference to FIG. Next, with reference to FIGS. 6 and 7, a method of determining a corresponding channel for transmitting a requested program using a logical node ID will be described in two embodiments.

As shown in FIG. 5, a method for inserting, transmitting, and using a Boolean node ID in accordance with the present invention is shown. The process begins at step 502 where a unique logical node ID is generated for each node and the logical node ID is inserted into the data stream. Then, at step 504, the logical node ID signal is transmitted over the information network 108 as part of the data stream. Then
At step 506, a data stream including the logical node ID is received at the subscriber station. Then, at step 508, the subscriber station creates a new message containing the logical node ID using the received logical node ID. The message created in step 508 is then sent to the headend in step 510. The combiner or headend uses this message in step 512 to establish Boolean node membership, and thus the network topology is recognized by system 100c. The system 100c then
Using the information stored in the head end, the TPM 102b and the DVM module 1
06b switches the data stream so that the program is correctly routed, even if changes are made to the network, either manually or automatically. In other words, using the logical node ID, the TPM 102b and the DVM module 10
6b can reliably send data to the appropriate subscriber station.

FIG. 6 shows a master SC for identifying an SCM corresponding to a subscriber station.
6 is a flowchart illustrating an embodiment in which the role of M and the role of hub when providing channel allocation information to a subscriber station are removed. Eliminating such operations has the advantage of reducing the amount of time required to initialize the VOD service. These steps are eliminated by storing the channel location information at the subscriber station and the address of the corresponding SCM. This information can be stored in a non-volatile memory such as a flash memory commonly found in subscriber stations, such as digital set-top boxes.

Returning to FIG. 6, in step 602, the user requests a VOD according to the method of the corresponding subscriber station. In step 604, the subscriber station reads the program map table (PMT), and in step 606 receives the periodic transmission of the logical node ID. In step 608, the IP address of the SCM stored in the subscriber station and its listener port number are
User Datagram Protocol (UDP) between SCM and subscriber station
Or TCP-Transmission Control Protocol) connection. Step 6
At 10, the program transmission is performed until the program transmission ends at step 612.

FIG. 7 illustrates a video-on-demand (eg, transmission of a movie or other video program) between the set-top box (part of the subscriber station) and the headend 304.
5 is a flowchart illustrating communication for requesting and receiving a (VOD) service. At step 702, the user requests a VOD service with the appropriate input into the set top box. In step 704, the corresponding hub answers the request for VOD by identifying the SCM functioning as the master SCM from the hub storage information. At step 708, the subscriber station initiates communication with the master SCM to establish a connection between the master SCM and the subscriber station. The connection is TCP / IP, a set of protocols
It is preferably established according to the User Datagram Protocol (UDP). At step 710, the hub arranges a channel for transmission of the video program requested by the hub corresponding to the subscriber station. Also at step 710, the master SCM uniquely locates the requested program by placing a program identifier (PID). In step 712, the transmission of the logical node ID is performed periodically, for example, every tenth of a second, so that the logical node ID can be expected to be received by the subscriber station. In the alternative embodiment, shown in dashed lines in FIG. 7, the channel for transmission of the requested video program from the corresponding hub to the subscriber station, and the program identifier (PID) are predefined (step 730). For example, a copy of a delivery packet having a given channel and PID may be stored at a subscriber station using local memory to reduce the latency of initiating a two-way session, in which case:
The content provides a temporary copy of the information contained in the delivery packet. In that case, steps 700-710 may be replaced by a single step 730 identifying the predetermined channel and PID, and the method continues with the information in step 714.

Once the subscriber station receives the logical node ID, it has the necessary information to communicate with the corresponding SCM, and in step 714 the UDP connection between the master SCM and the subscriber station is terminated. In step 716, the UDP
A connection is established between the identified SCM and the subscriber station. Step 7
Once established at 16, the SCM to the requesting subscriber station
Until the transmission of the request program is completed in step 720.
This is performed at step 718.

It will be appreciated that the specific mechanisms and techniques described are merely illustrative of one application of the principles of the present invention. Numerous additional modifications may be made to the described methods and apparatus without departing from the true spirit of the invention.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of a system using the principles of the present invention.

FIG. 2A is a block diagram of a first embodiment of a system using the principles of the present invention, wherein a broadcast satellite is used for some transmission networks. FIG. 2B is a block diagram of a second and preferred embodiment of a system using the principles of the present invention, wherein a video-on-demand network is used for the transmission network.

FIG. 3 is a high-level block diagram illustrating in more detail the headend including the session control manager, hub and subscriber stations of the second embodiment.

FIG. 4 is a high-level block diagram showing in more detail the session control manager, hub and subscriber stations of FIG. 3, and the logical nodes into which they are divided.

FIG. 5 is a flowchart illustrating a general method for transmitting logical node identification signals and configuring them and using them to transmit data signals.

FIG. 6 is a flowchart illustrating the operation of a system based on the principles of the present invention.

FIG. 7 is a flowchart illustrating the operation of a system based on the principles of the present invention.

[Explanation of symbols]

100a, 100b, 100c system 102, 102b logical node ID generator 104b server 104 signal source 106b digital video modulator (DVM) module 106 combiner 108, 302 information transmission network 110, 110b information distributor 120-132 signal line 202, 202a, 202b, stream channel 204 control channel 204a, 204b return channel 204a-204n telephone line 210a-210n descrambler 212a-212n device 214a-214n telephone 220, 220a-220n set-top box 222 control channel modem (CCM) 224, 314 , 315, 316, 317 Session Control Manager (SCM
) 304 cable head end 305-308, 312 subscriber station 309-312 hub

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GE, GH, GM, HR, HU, ID, IL , IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, TJ, TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZWF terms (reference) 5C064 BA07 BB05 BC10 BC17 BC18 BC20 BC22 BD08 BD09

Claims (21)

[Claims] 1. A method for controlling a plurality of sessions on a spectrum reusable network between a subscriber station and one of a corresponding plurality of nodes arranged between the video-on-demand system and said subscriber station. A video-on-demand system for transmitting a request program to said requesting subscriber station by one of said managers: identifying a correspondence between each of said nodes and a corresponding one of said session control managers. A video-on-demand system comprising a logical node assigner for assigning a logical identity to each of said nodes. 2. A method for transmitting a request program in response to a request by said subscriber station in said network characterized by a channel reused in transmission between an intermediate node of the network and a corresponding subscriber station. Answering the request for the requesting program by sending from the intermediate node the network address of the requesting subscriber station to a control module; and transmitting the requesting subscriber station and the transmission of the request program. Allocating a channel to and from the intermediate node for identifying the requesting program to be received by the requesting subscriber station. Transmitting a child type identifier to the intermediate node based on spectrum reuse independently of the physical organization of the subscriber stations on the network; and wherein the program identifier and the logical type identifier are Transmitting the request program with the indicating information. 3. The method of claim 2, further comprising transmitting the program identifier and the logical type identifier from the requesting subscriber station to the control module. 4. The method of claim 3, further comprising: switching the request program transmission to a logical node and switching a program identifier transmitted from the requesting subscriber station to the control module. 5. Apparatus for transmitting a video program over a network in response to a request for a video program from a subscriber station connected to the network by a corresponding one of a plurality of hubs, each control comprising: A plurality of control modules for controlling transmission of the request program to the plurality of subscriber stations; and a node identification value indicating a correspondence between the hub and a corresponding one of the control modules. A node identifier for assigning to the 6. The node identifier assigns the node identification value by periodically transmitting the node identification value to each of the hubs of the network.
The device of claim 5. 7. The apparatus of claim 5, further comprising a master control module for assigning said control module to at least a first corresponding one of said hubs. 8. The master control module replies to a request from any one of the subscriber stations by identifying a corresponding one of the control modules to the requesting subscriber station. 7 device. 9. The apparatus of claim 8, wherein said node identification value comprises a single packet for all buses. 10. The apparatus of claim 7, wherein the first subscriber station sends the node identification value to the master control module. 11. The master control module may use the node identification value transmitted by the subscriber station to the master control module as a corresponding one of the control modules to the first subscriber station. The apparatus according to claim 10, wherein the request program is transmitted. 12. The master control module uses the node identification value sent by the subscriber station to the master control module to transmit a DV to the first subscriber station for transmitting the request program.
The apparatus of claim 11, wherein M and a channel are selected. 13. A hybrid fiber optic and coaxial network for broadcasting video programs from a headend to a plurality of subscriber stations, characterized by a hub for connecting the coaxial and fiber optic portions of the network. , At least first and second channels located between each of the hubs and the corresponding subscriber station, and for responding to a program request from the subscriber station by transmitting a request program. The network further characterized by the following: a first for periodically providing a logical node identifier to identify a correspondence between a hub and a control station corresponding to the requesting subscriber station;
Means for answering the program request from one of the requesting subscriber stations and providing a frequency and a PID indicating the requested program to the requesting subscriber station; And a third means for responding to the second means for transmitting the request program to be received by the requesting subscriber station; and a hybrid network coaxial with optical fibers. 14. The program requested by the subscriber station connected to the network by the network controller allocating a channel for transmitting a request program from the network controller to the requesting subscriber station. An apparatus for transmitting over a network, the network characterized by a first bandwidth between the apparatus and the network controller, and a network between the network controller and the subscriber station. Wherein the second bandwidth is lower than the first bandwidth and the apparatus answers the requesting subscriber station's request with the request program; Subscriber stations A program identifier that uniquely identifies the request program for transmission by the network controller; and uniquely identifies the network controller as a corresponding network controller for reception by the network controller; and Transmitting a logical identifier that is independent of the physical organization of the subscriber station, and the apparatus further causes the request program to be transmitted for reception by the requesting subscriber station. 15. The requesting subscriber station answers the request with the request program and assigns the program identifier, the logical identifier and one of a plurality of other control modules for transmitting the request program. 15. The apparatus of claim 14, further comprising: a master control module. 16. Identify a modulator that communicates with a first subscriber station in a network characterized by channels reused in transmissions between a headend having a plurality of modulators and a plurality of subscriber stations. Providing a plurality of logic node identification numbers; assigning a logic node identification number to a data stream; and the first from the head end using one of the plurality of modulators. Transmitting the assigned logical node identification number along with the data stream to the subscriber stations of the other. 17. sending from the first subscriber station to the headend the logical node identification number and information identifying the first subscriber station; and 17. The method of claim 16, further comprising: using the logical node identification number from the first subscriber station to identify the modulator transmitting from a plurality of communicating modulators. 18. The method of claim 16, wherein said headend comprises a digital video modulator using DVM quadrature amplitude modulation (QAM). 19. The method of claim 16, further comprising the step of identifying a given channel and identifying a packet identification number from a copy of the distribution packet stored at the subscriber station. 20. Identify a modulator that communicates with a first subscriber station in a network characterized by channels reused in transmissions between a headend having a plurality of modulators and a plurality of subscriber stations. Connecting the first subscriber station to the network at a first location for communication; receiving a logical node identification number with a data stream at the first subscriber station. Sending the logical node identification number and first station identification information to the headend; and transmitting the logical node identification number to identify a modulator of the transmission communicating with the first subscriber station. Using. 21. Disconnecting said first subscriber station in communication at said first location from said network; reconnecting said first subscriber station with said network at a second location for communication. Receiving a logical node identification number with a data stream by a first subscriber station; sending the logical node identification number and the first station identification information to the headend; and the first subscriber 17. The method of claim 16, further comprising using the logical node identification number to identify a modulator of a new transmission in communication with a station.